failed data readings and other issues
Champion
Joined: Aug 2009
Posts: 3,015
Likes: 8
From: Western NY,
crank position sensor can cause that...there is even a video on youtube showing one hooked to a computer giving whacky results.. the other sensor in the distributor could possible cause this to I believe.
(I picked up a new CPS from ebay....$21 shipped... They want like $47 at advance auto...)
(I picked up a new CPS from ebay....$21 shipped... They want like $47 at advance auto...)
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Professional
Joined: Nov 2011
Posts: 232
Likes: 0
From: West Virginia
Cam sensor in the distributor is new from rockauto, don't remember brand, and crank sensor was the last thing,new, put on with the motor. I got it from advanced and don't remember that brand either. I know dodge woulda been best bet for all but I only have time to work on it on weekends and they are closed.
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Professional
Joined: Nov 2011
Posts: 232
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From: West Virginia
I have all the old sensors. They were replaced just because its a new motor and wanted to put new ones in that are hard to get to. I can swap one at a time when I get home. Unfortunately i have to travel back to where grew up on the weekends to the mechanics shop. im in that area now so will have to wait until tomorrow to get back to where the parts are.
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Professional
Joined: Nov 2011
Posts: 232
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From: West Virginia
Which line is it? I honestly don't know what all those canisters are lol and they pulled the main vac from the motor over there and checked somethin. not sure what
Site Moderator-Dodge Tech
Joined: Sep 2010
Posts: 3,724
Likes: 22
From: Nashville, Tennessee
Follow the one to the vacuum source and it will be the other one. The purge valve is on the passenger side. Make sure the two arent switched either. The valve will be marked.
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Professional
Joined: Nov 2011
Posts: 232
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From: West Virginia
So i checked the solenoid lines. They are connected correctly according to a diagram I found and when pulled noticed nothin out of the ordinary. I did find that the ground near the pcm and all that stuff was pretty loose. Not tight at all. Tightened it up but don't know if that would effect anything. Gonna pull the crank sensor and see if everything is intact. Gonna test it even though I'm aware that it can test correctly and still not work. Debating buying one from the store and swapping to troubleshoot. i dont have my old one with me. I do have a new o2 and idle air valve in the truck.
Legend
Joined: Jul 2011
Posts: 8,259
Likes: 4
From: Austin, TX
So I currently had the truck on the computer diagnosing my miss issue. I initially was told I had a miss on 5 and 7 but was wrong. I had a miss on every cylinder, only at idle. Get it up to around 1000 rpm the misses go away. At one point at rpm above idle there was a slight miss on a few cylinders. When bringing up rpm idle air valve wasn't keeping up. Brought rpm up to different points and idle air valve was always lower and fluctuating a bit. It never caught up. AND the big one, spark advance was jumping around. We don't know if the timing is off because the computer is going crazy OR its adjusting itself because of somethin else that is bad. Here are the failed tests:
Bank 1 sensor 1 o2 half cycle
-measured 10 minimum 56
- failed
Failed purge monitor ic step shift
-measured 7 minimum 254
Failed purge monitor rpm shift
-measured value 0 minimum 65527
And again, all cylinders mis at idle and spark advance jumps around
Reset: adaptive fuel and IAC - no results so far
I do have a small weld leak a few inches before the precat o2. Going to fix it tomorrow. Everything else checked out.
So what does everyone think? What should be first thing to attack? What do those failed tests monitor or mean? What else should I get readings on to help diagnose? The guy I'm working with said he's more than happy to plug me in and get the readings. Since he doesn't know what to start with he wants me to share as much as needed to diagnose and he will learn in the process.
Thanks in advance.
Bank 1 sensor 1 o2 half cycle
-measured 10 minimum 56
- failed
Failed purge monitor ic step shift
-measured 7 minimum 254
Failed purge monitor rpm shift
-measured value 0 minimum 65527
And again, all cylinders mis at idle and spark advance jumps around
Reset: adaptive fuel and IAC - no results so far
I do have a small weld leak a few inches before the precat o2. Going to fix it tomorrow. Everything else checked out.
So what does everyone think? What should be first thing to attack? What do those failed tests monitor or mean? What else should I get readings on to help diagnose? The guy I'm working with said he's more than happy to plug me in and get the readings. Since he doesn't know what to start with he wants me to share as much as needed to diagnose and he will learn in the process.
Thanks in advance.
Bank 1 sensor 1 O2 half cycle -measured 10 minimum 56 - failed
From Snap ON MT2500 manuals -Domestic and Chrylser:
Measurements should be between 0.00 and 520 Mv (or 0.520 v). 0.00 is very lean, and .520 is pig rich. But it should vary constantly. Mine normally runs from 0.38 to .55 at idle after it is warm.
Failed purge monitor ic step shift -measured 7 minimum 254
According to Snap On, the values here should be "normal," "flow," and "block." Have it tested through these modes and see if it actually fails. It does not appear to be a stepping motor, only a solenoid from what I am reading. I cannot find any reference to measured steps here.
Failed purge monitor rpm shift -measured value 0 minimum 65527
Once again, from what I can find, these values do not look correct. I find where this is measured in Mv, range should be fomr 0.00 to 670 Mv.
And again, all cylinders mis at idle and spark advance jumps around
Reset: adaptive fuel and IAC - no results so far.
Resetting these should go back to wahtever is stored in PCM. You have to go back and re-read these values to see what they are.
IAC should read steps from 1 through 255. Number should be higher for higher idle speed.
To reset fuel sync, I shoe that at 1875 rpm, turn distributor so that it reads 0 degrees. Seems like high rpm for me, but read it that way twice.
Depending on the computer being used, the cam sensor and IAC can be reset. I would consider trying this. Then I would look at resetting fuel sync. If it is a Snap On, either the MT 2500 series or the newer version that replaced it, it will make these adjustments. Something is not reading correctly, and with misfires, I suspect timing to plugs or to injectors.
Who has the computer that you were readiing this on? Did you clear all the misfire and other codes as well? I know that every time I use mine I have to drag out the books. I don't use it often enough (thank goodness) to keep it all in memory!
And loose grounds can cause all sorts of issues.....tighten the snot out of it and make sure the connection is clean!
Hope this helps.
Last edited by gdstock; Mar 4, 2012 at 11:13 PM.
